The subject matter of the present invention pertains to means for indicating the relative position of a joystick-type control stick commonly employed to control the operation of various kinds of electronic equipment.
Normally, such devices comprise a pivotably mounted control stick that is mechanically coupled to one or more variable electronic circuit elements such as variable resistors or potentiometers. Pivotal movement of the stick about a fulcrum produces a corresponding change in the value of the circuit elements, with the changing value being employed usually to produce electronic analog signals that are representative of the stick's position of the stick relative to one or more planes of reference.
The disadvantages of such devices are that the output signals initially produced are of an analog rather than digital nature and must therefore undergo a subsequent conversion before being useful in a digital environment, the output signals are often subject to contamination with noise signals generated by the movement of mechanical contacts within the variable circuit elements, and the variable elements are subject to mechanical and electrical deterioration brought on by wear and aging. Moreover, free movement of the control stick, a very desirable feature with this type of device, is often hindered by inertia and frictional forces acting among the various mechanical components.
A contactless positional encoder such as that disclosed by Wester U.S. Pat. No. 3,886,361 overcomes some of the above-mentioned disadvantages; however, the output signal produced is still of an analog rather than digital nature. Accordingly, a need still exists for a non-mechanical control stick device capable of producing directly a digital signal that is representative of the relative position of the stick.